textproduct: Rapid City

KEY MESSAGES

-Warmer through Tuesday, then becoming unsettled and cooler

-Isolated TS possible through Tue across western SD, with the potential for severe storms

-Elevated to near critical fire weather conditions through Tues across portions of northeast WY

-Wildfire smoke is expected to linger much of the week, with thicker smoke at times across the western third

UPDATE

Issued at 940 PM MDT Sun Aug 9 2026

Fast westerly flow aloft combined with increasing low level moisture per easterly low level flow can be expected the next couple days. Weak impulses will ride the flow, supporting daily low chances for TS across western SD. TS chances are highly conditional and will hinge on weather the passing impulses can produce enough forcing to break the capping inversion. If storms do get rooted in the BL, given MLCAPE of 2000-3000 J/kg and bulk shear around 50 knots, isolated severe storms would be possible with damaging winds and large hail. Cams hint at this the next few days. Hot Monday and Tues with highs mainly in the 90s, hottest over northeast WY. As western CONUS troughing develops later in the week, monsoon moisture will be directed into the region, supporting cooler conds with increasing chances for showers and storms after Tue. This should also help push wildfire smoke more north and out of the FA for a period.

DISCUSSION

(This Afternoon Through Saturday) Issued at 1150 AM MDT Sun Aug 9 2026

It has been a day of waiting and seeing if thunderstorms initiate. As of 1PM, one cell was been able to develop in Butte County north of the Black Hills. Looking ahead, still can't completely rule out more isolated storm development near the northern Black Hills. There are just enough ingredients available but with how dry the area is and how warm the atmosphere is, any vertical motion that happens has a lot to overcome.

For tonight, central SD could see thunderstorms drift in from the north. Some of those storms could be strong to severe, the SPC has placed a Slight Risk (level 2 of 5) for these forecasted storms.

Monday and Tuesday look similar, with highs mostly in the upper 80s to 90s. Zonal flow will keep the daily chances for afternoon storms in place over the CWA. SPC has placed a marginal (level 1 of 5) over the SD counties for both Monday and Tuesday.

The SPC has also placed a risk of severe weather on Wednesday centered over SW SD. Model forecasts suggest that scattered thunderstorms will most likely develop in the afternoon along an axis of moderate instability from western Nebraska into southwestern South Dakota. The storms will be supported by a mid- level shortwave trough moving across the north-central U.S. Moderate deep-layer shear near the instability axis should support a severe threat during the afternoon and evening.

Unsettled pattern under zonal flow will give the area cooler temps and daily chances for rain and storms for the second half of the week.

AVIATION

(For the 12Z TAFS Through 12Z Tuesday Morning) Issued At 522 AM MDT Mon Aug 10 2026

MVFR/IFR conditions in low stratus and patchy fog will continue to develop over the western and south central SD plains through the early morning hours. This cloud cover/fog will dissipate after 15z with conditions improving to VFR.

There is also a chance for TSRA over western SD and the Black Hills after 21z this afternoon. Confidence in TSRA impacting the KRAP terminal is too low to mention in TAFs at this time. LCL MVFR conditions, strong and erratic wind gusts, and hail could be encountered near any storms that develop.

UNR WATCHES/WARNINGS/ADVISORIES

SD...Red Flag Warning from noon today to 9 PM MDT this evening for SDZ322. WY...Red Flag Warning from noon today to 9 PM MDT this evening for WYZ314>317.